The subject matter of the present disclosure relates to lamps and lighting devices and, in particular, to embodiments of a lamp that combines a high-efficiency light source with thermal management using an active cooling device, e.g., a synthetic jet ejector.
Incandescent light bulbs have been available for over 100 years. Other types of light sources for lamps, however, show promise as commercially viable alternatives to the incandescent light bulb. Lamps that utilize high-efficiency light devices (e.g., light-emitting diode (LED) devices) are attractive because these devices save energy through high-efficiency light output. Moreover, LED devices and other solid-state lighting technologies offer performance that is superior to incandescent lamps. For example, the useful lifetime (e.g., lumen maintenance and reliability over time) of incandescent lamps is typically in the range about 1000 to 5000 hours. Lamps that utilize LED devices, on the other hand, may operate in excess of 25,000 hours and, perhaps, as long as 100,000 hours or more.
Several factors can affect the quality of performance of lamps that utilize LED devices as the light source. For example, many LED devices use a direct current (DC) input. Lamps with LED devices must generate a DC input from the alternating current (AC) input, which is the common power supply in home and/or office settings. This feature can affect operation of the LED devices. For example, ripple and other anomalies that might prevail in the DC input due, at least in part, to conversion of the AC input to the DC input as well as in connection with other operational components in the lamp. Such anomalies can affect performance of the LED devices.
LED devices are also sensitive to high temperatures, which can affect both performance and reliability as compared with incandescent or halogen lamps. However, LED devices are known to convert a significant portion of the DC input to thermal energy. Lamps that use LED devices often include an efficient thermal management system that dissipates heat to maintain the light source at an acceptable operating temperature and to achieve adequate lifetime. Physical constraints on size and packaging of the lamp, however, further complicate the task of heat dissipation. For example, regulatory limits define the maximum dimensions for an envelope in which all the lamp components must fit. This envelope limits choices for the design and layout of features and devices that would otherwise dissipate heat properly from the lamp.
To this end, thermal management devices that dissipate heat in lamps that deploy LED devices are known. Some of these devices use conventional fans, piezoelectric elements, and synthetic jet ejectors. The latter type, i.e., synthetic jet ejectors, utilize a diaphragm that flexes, e.g., in response to an AC input. Flexing of the diaphragm propagates airflow over the LED devices and/or throughout the lamp. This configuration of elements offers efficient and versatile cooling at a local level, e.g., the light source. However, although packaging of the synthetic jet ejector particularly suits the envelope and other construction of lamps with LED devices, this type of cooling mechanism typically utilizes expensive components. These components may sometimes fail to meet cost and sustainability requirements necessary to make lamps with LED device and solid state technology a robust alternative to incandescent and halogen-based bulb technology.